RESEARCHERS AT Indian Institute of Science Education and Research (IISER) now know why a hydra, the freshwater invertebrate animal, can easily perform somersaults. Commonly found in freshwater such as ponds in tropical countries, evolutionary biologists have a special interest in studying hydra. One of the reasons being, their special locomotive powers than their fellow phylum cnidaria members like jellyfish. A recent study, led by researchers from biology and physics departments of IISER, has confirmed that the hydra's somersaulting abilities are directly linked to its strong shoulders. The shoulder region, where the hydra's tentacles emerge, was found to be three times stiffer than the rest of its body, concluded the paper published in the Journal of Experimental Biology. Hydra has a cylindrical polyp-shaped slender body, measures 6 mm to 10 mm in length and about 1 mm in thickness. Upon closely studying the physical properties of the hydra's body column, scientists noted a variation in the stiffness in the tissue. "When trying to study the response of hydra tissue and its regenerating ability, we discovered that the tissue stiffness was not uniform across the body column," said Shivprasad Patil from the department of physics. Though plants and animals are multicellular organisms, their locomotive abilities largely differ from one another. "It is not clear when this difference first occurred between these organisms during their evolution. The invention of movement by animals is an important milestone," said evolutionary biologist Sanjeev Galande. Fellow IISER researcher Apratim Chatterji and Irit Sagi from Weizmann Institute of Science now suggest multiple new possibilities to deepen understanding of evolution of movement in animals, including highly evolved ones.
